scroll/src/common/strings_test.ts

import { importDefaultForRuntime, ITestBase } from './mod.ts';
import {
	chars,
	ctrl_key,
	is_ascii,
	is_control,
	strlen,
	truncate,
} from './strings.ts';

const t: ITestBase = await importDefaultForRuntime('test_base');

t.test('chars fn properly splits strings into unicode characters', () => {
	t.assertEquals(chars('😺😸😹'), ['😺', '😸', '😹']);
});

t.test('ctrl_key fn returns expected values', () => {
	const ctrl_a = ctrl_key('a');
	t.assertTrue(is_control(ctrl_a));
	t.assertEquals(ctrl_a, String.fromCodePoint(0x01));

	const invalid = ctrl_key('😺');
	t.assertFalse(is_control(invalid));
	t.assertEquals(invalid, '😺');
});

t.test('is_ascii properly discerns ascii chars', () => {
	t.assertTrue(is_ascii('asjyverkjhsdf1928374'));
	t.assertFalse(is_ascii('😺acalskjsdf'));
});

t.test('is_control fn works as expected', () => {
	t.assertFalse(is_control('abc'));
	t.assertTrue(is_control(String.fromCodePoint(0x01)));
	t.assertFalse(is_control('😺'));
});

t.test('strlen fn returns expected length for multibyte characters', () => {
	t.assertEquals(strlen('😺😸😹'), 3);
	t.assertNotEquals('😺😸😹'.length, strlen('😺😸😹'));

	// Skin tone modifier + base character
	t.assertEquals(strlen('🤰🏼'), 2);
	t.assertNotEquals('🤰🏼'.length, strlen('🤰🏼'));

	// This has 4 sub-characters, and 3 zero-width-joiners
	t.assertEquals(strlen('👨‍👩‍👧‍👦'), 7);
	t.assertNotEquals('👨‍👩‍👧‍👦'.length, strlen('👨‍👩‍👧‍👦'));
});

t.test('truncate shortens strings', () => {
	t.assertEquals(truncate('😺😸😹', 1), '😺');
	t.assertEquals(truncate('😺😸😹', 5), '😺😸😹');
	t.assertEquals(truncate('👨‍👩‍👧‍👦', 5), '👨‍👩‍👧');
});